The invention relates to extruders in general, especially to extruders which can be used to make shaped articles from plastic material. More particularly, the invention relates to improvements in connections between the screw of an extruder and a drive which serves to impart to the screw a rotary and, if necessary, a reciprocatory movement.
It is well known to plasticize synthetic plastic powders or granulates in an extrusion cylinder wherein the material is heated while being acted upon by an extruder screw. The latter receives motion from a drive whose output element is coupled to the screw. As a rule, the end faces of neighboring end portions of the screw and output element are formed with grooves for a torque-transmitting wedge, and the end portions are then confined in a two-piece sleeve. A drawback of such couplings is that they are prone to malfunction. The useful life of the wedge is short and the end portion of the screw is likely to crack or break in response to the application of forces which arise if the axis of the output element does not coincide with the axis of the screw.